Caged luminophores, whose luminscence is partially or completely quenched by a quencher but can be recovered upon cleavage of the quencher under certain stimulus such as UV or thermal treatment, are a type of typical photoactivatable materials and have been well studied and applied in many technological fields especially those related to biological applications such as macromolecular movement tracking and super-resolution imaging. For macro-molecules tracking, caged compunds can highlight a partistic area or organelle to monitor and study. For super-resolution imaging, caged luminophores can be turned on and off to record signals which accumulate to produce the super-resolution imaging. 2-Nitrobenzyl group is the most representative quencher for caged luminophores. Because of strong electron-withdrawing ability of 2-nitrobenzyl group, the emission of luminophore in the caged compound is quenched through photo-induced electron transfer (PET) process. These concepts have already demonstrated by traditional fluorophores such as BODIPY, fluorescein and rhodamine. However, those conventional fluorophores are suffered from aggregation-caused quenching (ACQ) effect, in which their emission is weaken or quenched when the molecules are aggregated in a condensed phase. Such ACQ effect in conventional fluorophores has greatly limited to utilize them in solid state or biological applications.
Inventions of caged luminophores have been reported in prior art, examples of which have been reported by Stefan W. Hell (U.S. Pat. No. 8,617,827 B2), Wen-Hong Li (U.S. Pat. No. 7,304,168 B2, U.S. Pat. No. 8,153,103 B2) and Joan C Politz (WO1998006875 A1).